Convertible saw blade

ABSTRACT

A convertible saw blade which may have a curvilinear cutting portion for self starting. The cutting edge of the blade is provided with customary teeth having angular sets to the opposite sides of said body. The teeth are used for relatively soft material. A cutting rod of wear resistant material with abrasive particles therein is detachably fitted over the teeth between the tips of the teeth for use of the blade with harder materials.

United States Patent Doty Aug. 29, 1972 [54] CONVERTIBLE SAW BLADE vFOREIGN PATENTS OR APPLICATIONS [72] Inventor: Myrle M. 'Doty, 818Stevens Ave., 536,548 12/1955 Italy 125/18 Sycamore, Ill, 60178 770,8003/1957 Great Britain ..145/33 E Filed: Feb. 25, 1971 Appl. N0.: 118,890

us. c1. ..5l/l81 R, 7/13 R, 125/18 1m. C1. .132411 25/00 Field of Search..l25/l8; 51/181; 145/33 E;

References Cited UNITED STATES PATENTS Maier ..5l/l81 PrimaryExaminerHarold 1). Whitehead Att0rneyMann, Brown, McWilliams & Bradway[5 7] ABSTRACT A convertible saw blade which may have a curvilinear 4cutting portionvfor self starting. The cutting edge of the blade isprovided with customary teeth having angular sets to the opposite sidesof said body. The teeth are used for relatively soft material. A cuttingrod of wear resistant material with abrasive particles therein isdetachably fitted over the teeth between the tips of the teeth for useof the blade with harder materials.

11 Claims, 8 Drawing Figures CONVERTIBLE SAW BLADE The present inventionis directed to new and useful improvements in convertible saw bladeswhich are specially adapted for use in cutting either hard or softmaterials.

The present invention is particularly concerned with improvements whichallow a blade to be used with relatively soft materials such as wood andsoft metals while the blade is convertible for use with harder materialssuch as glass, hard metals, etc. The invention may be embodiedadvantageously with self starting curvilinear blades of the typedisclosed in my prior US. Pat. No.

Other purposes of the present invention are to pro.- vide a saw blade ofthis class which may be used easily with a power saw such as a saber sawor with a simple handle, to provide a novel mounting for a wearresistant, abrasive particle carrying cutting rod which provides supportfor the rod along the length thereof while allowing simple coupling anduncoupling of the rod to the support and while at the same timeproviding for air circulation at the adjacent areas of the support androd to dissipate heat from the rod.

These and other purposes of the present invention will become moreapparent in the course of the ensuing specification and claims whentaken with the accompanying drawings, in which:

FIG. 1 is a side view of a typical saw blade with which the presentinvention may be used; 7

FIG. 2 is a side view of a saw blade incorporating the principles of theblade illustrated in FIG. 1 while illustrating the use of a cutting rodattached to the blade body in FIG. 1;

FIG. 3 is an end view of a portion of the saw blade body illustrated inFIG. 2 and taken along thesection line 3-3 of FIG. 2;

FIG. 4 is rear view of one end of the rod saw illustrated in FIG. 2,taken on the section line 4-4 of FIG.

FIG. 5 is an end view of the'coupling facilities at the forward end ofsaid saw body and taken on the section lines 53 of FIG. 2;

FIG. 6 is a side view of a modified tension-applying coupling for therod and blade body illustrated in FIGS.

FIG. 7 is a side view of a modified form of the invention; and

FIG. 8 is an exploded view of a coupling shown in FIG. 7.

Like elements are designated by like characters throughout thespecification and drawings.

With specific reference now to the drawings, and in the first instanceto FIG. 1, the numeral 10 generally designates an elongated blade bodywhich may be of plate-like steel stock. The blade body has a shank endportion 11 which is formed with a holding aperture 12, and a shoulder 13for reception within the chuck of a portable power saber saw. which isrepresented in dotted lines at 14 in FIG. 2. It should be understoodthat the general configuration of the shank end portion 11 is intendedto be representative of a conventional shank end portion of a saw bladewhich is used with a reciprocating saber saw.

In lieu of use with a power tool, the blade maybe used with amanipulating handle generally designated at H in FIGS. 2 and 7.

The blade body 10 has one sideedge 15 thereof formed with saw teeth10awhich are given a rearward rake or a rake extending toward the shankend portion of the body. This side edge of the blade body has arectilinear expanse from the point generally designated at A andextending to or near the shank end portion. This rectilinear edgeportion may form a major part of the overall length of the saw blade ora minor part thereof. The toothed side edge 15 of the blade body fromthe point A to the forwardend 16 has a curvilinear form and may bestruck about a center at B which is positioned inwardly of the extremeend of the blade body and to one side of the blade body, as described inmy US. Pat. No. 3,477,479. This curvature or the side edge between theend 16 and point A is 'such that it is tangent to the rectilinearportion of the I toothed edge.

The blade as disclosed in FIG. 1 is especially adapted for cutting woodand soft metal. The curvature of the blade, as disclosed in said patent,enables the self starta ing characteristics of the blade. The blade, asdisclosed in said patent, may also be used for conventional cuttingoperations.

In accordance with the present invention an elongated rod 17 is adaptedto be fitted over the teeth of the blade. Rod 17 is formed from a wearresistant material such as tungsten carbide. Materials of this type forcutting hard metals, glass, and other hard materials are known to theart. One example is disclosed in US. Pat. No. 3,023,490. Material ofthis type carries cutting or abrasive grains which are embedded in amatrix of material. Material of this type is available in elongatedrod-like form and has been known as an attachment for a conventionalhack saw as a substitute for the normal hack saw blade.

Cutting rod 17 is positioned over the teeth of the saw blade. The teethof the saw blade are given a set so as to define a more or less V-shapedvalley therebetween as will be seen in FIG. 3. This set is such that thetips of the teeth define a cross-sectional width greater than thethickness of the saw blade. Adjacent teeth in the blade are given theset by flaring them outwardly to opposite sides of the saw blade. Thecutting rod, which preferably is also slightly greater than the width ofthe body of the blade, is received in this valley defined between teeth,as will be seen in FIG. 3. Rod 17 preferably has a diameter (FIG. 3)slightly greater than the distance between the outermost tips of theteeth. The tips of the teeth .then hold the rod against lateraldisplacement. Couplings, as hereinafter described,

tightly against the teeth. Thus the rod is formed in curvilineardisposition which enables the rod to cut through hard materials in aself starting fashion. The use of the saw teeth, as a support for therod, not only provides the rigid curvilinear support but also provides aplurality of heat dissipation air spaces between teeth and between therod.

The curvilinear nature of the blade allows the rod to be stretchedagainst the curve of the blade and the rod is, therefore, easily fittedinto its cutting position while being supported by the blade. With thecurvilinear nature of the blade, the precision of fit between the endattachments, teeth and rod need not be as precise as would be the casewith a straight saw tooth cutting edge.

Rod 17 is adapted to be held on the blade body and against the teeth bymeans of detachable couplings at opposite ends of the blade body. Forexample, a first coupling designated generally at 18 is carried by theshank end. As will be noted in FIGS. 2 and 4, coupling 18 is comprisedof a strap 19 having a slot 19a through which the shank end of the bladeis received. The strap is adapted to bear against a shoulder 20 at theshank end. Slot 19a has a configuration matching the crosssection of theblade shank next to the shoulder, as shown.

One end of the rod 17 carries an abutment in the form of a shorttransversely extending end piece 21 which is formed on a reduced end 22of the rod. The reduced end 22 is received through a slot 23 openingthrough the bottom of the strap.

The other end of the rod is held on the other end of the blade byanother detachable coupling generally designated at 24. Coupling 24 maytake the form of a strap 25 shaped to fit over and embrace the forwardend of the blade body. A notch or recess 25a is formed in the top sideedge of the blade so that one edge of the strap may be seated therein torestrict displacement of the strap from the blade. The saw tooth side ofthe strap carries a laterally extending flange 26 having an aperture.The reduced other end 27 of rod 17 is received through this aperture andis threaded. A nut 28 is threaded on this end 27 and is adapted to bearagainst flange 26. By rotating nut 28, tension is applied to the rod 17so as to draw it snugly against the teeth 10a.

FlG. 6 shows a modified tension applying strap for rod 17. In FIG. 6 thereduced end portion 27 of rod 17 at the outer end of the blade isprovided with an abutment in the form of a transversely extendingcrosspiece 29 similar to piece 21 in FIG. 4. A cap 30 is received overthe outer end of the blade in a fashion similar to the strap 25 in FIG.2. This end of the blade may be provided with a notch or undercut 30a tofacilitate positioning of the cap on this end of the blade.

In FIG. 6 cap 30 carries an outwardly extending projection which isthreaded to define a bolt 31. A nut 33 is threaded on the bolt and isadapted to bear against a sleeve 34 which is freely received on thebolt. Sleeve 34 includes a slotted end similar to the slot 23 in FIG. 4for receiving the reduced end portion 27 of the rod. By rotating the nutoutwardly, pressure is exerted against the sleeve to exert tension onrod 17, while rotation in the opposite direction releases tension sothat the rod may be removed as desired. The outer end of the bolt may beupset as at 35 to prevent removal of the sleeve and nut therefrom.

FIGS. 7 and 8 illustrate a modified form of the invention.

In FIGS. 7 and 8 blade 10 and the shank end coupling 18 are identical tothat of FIGS. l-6. The cutting rod 17 is formed in the same mannerpreviously described except that the forward end portion of the rod ismodified for connection with a resilient coupling 36. Coupling 36includes a strap 37 having a slot 38 through which the forward end 39 ofthe blade is received in a fashion similar to the reception of the shankend of the blade through the strap 19. The side of the blade edgeopposite to the saw tooth side is slotted or undercut to provide ashoulder as at 40. The strap 37 may be seated in this slot, as is seenin FIG. 7. Strap 37 includes an aperture 41 through which the forwardend 42 of therod 17 is received. The forward end 42 of the rod 17 isthreaded as at 43 to receive a nut 44. A coil spring 45 is adapted to bereceived over the end 42 of the cutting rod 17 and compressed by the nut44 and strap 37.

In FIGS. 7 and 8, the cutting rod is positioned over the saw teeth inthe manner previously described and nut 44 is rotated to compress thespring 45. The spring exerts an outward biasing force on the nutand'thereby the rod 17 so that the rod 17 is resiliently tensioned alongits length. When the blade is used, rod 17 becomes heated and mayelongate due to the rise in 3 temperature. Spring 45 compensates forthis elongation by exerting tension along the length of the rod. Whenthe rod elongates, spring 45 will take up slack by pulling the rod 17outwardly and thus keep it against the backing defined by the saw teeth.

While the rod is preferably used with a curvilinear blade as described,the rod and couplings may be used with a straight saw blade as long asthe couplings are formed to hold the rod against the teeth of the blade.

The convertible blade is easily used for relatively soft materials byremoving the couplings from the ends of the blade in which case theblade may be used with a power tool for reciprocation thereof or with amanipulating handle. For harder materials the cutting rod 17 is easilyfitted over the blade by fitting the couplings at the ends of the bladesand then tensioning the rod against and within the tips of the bladetooth in the manner aforementioned. When the rod is used, the thicknessof the rod is such as to protect the teeth from' any substantial damagethereto as a cut is being made in relatively hard materials.

When the rod is used in self starting fashion, the couplings and rod maybe removed after a hole is formed through a workpiece. The blade is theninserted in the hole and the couplings and rod reattached.

I claim:

1. A convertible saw blade including an elongated flat saw blade havinga shank end portion formed and adapted for reception of a manipulatingmeans, the other end portion of said blade body being formed with acurved side edge, said curved side edge being formed substantially on aradius struck about a center positioned to one side of said body andinwardly of the extreme ends of said body, said one side edge being provided with saw teeth, said teeth having predetermined sets to the sidesof said body to define a generally V- shaped groove when the teeth areviewed from the end of said body, an elongated rod of wear resistantmaterial positioned over said side edge and between the tips of saidteeth, and means at the opposite ends of said body for holding said rodsnugly against said teeth.

2. The structure of claim 1 wherein said last named means includes meansfor tensioning said rod along the length thereof and pulling it snuglyagainst the teeth of said body.

3. The structure of claim 1 wherein said last named means includes adetachable coupling at the shank end of said body and a detachablecoupling at the other end of said body, one of said couplings includinga threaded fastener for applying tension to said rod.

4. The structure of claim 1 wherein said rod is formed from a tungstencarbide material having cutting grains embedded therein and exposedthrough the surface of said rod for a cutting action.

5. The structure of claim 1 wherein said rod is positioned against saidteeth while leaving air spaces extending from side to side of said bodybetween said teeth.

6. The structure of claim 1 wherein said rod has a cutting length with adiameter slightly greater than the span between adjacent saw teeth.

7. A saw blade for use in cutting hard metals, glass and equivalent hardmaterials, including an elongated body having a shank end portionadapted to be received by a manipulating means, one side edge of saidbody being provided with teeth with alternate teeth along said edgebeing bent outwardly to define a distance between alternate teethgreater than the width of said body, an elongated cutting rod of wearresistant, abrasive particle carrying material positioned over andbetween the tips of said teeth, and means carried by the shank end andother end portion of said body for applying tension to said rod to drawit snugly against and within the tips of said teeth, said rod having adiameter slightly greater than the thickness of said body.

8. The structure of claim 7 wherein said one side edge is curvilinear.

9. The structure of claim 7 wherein said teeth define saw teeth for usewith other materials when said rod is I detached from said body.

10. The structure of claim 7 wherein said detachable means includes astrap carried by said shank end of said body and a detachable strapfitted over the other end of said body, one end of said rod havingabutment means engageable with one strap, and the other end of said rodhaving adjustable abutment means for engagement with the other strap tothereby apply tension to said rod.

11. The structure of claim 7 wherein said rod is held on saidv blade atthe forward end of the blade by a resilient coupling providingtensioning forces to said rod to compensate for elongation. andcontraction of said rod due to temperature changes.

1. A convertible saw blade including an elongated flat saw blade havinga shank end portion formed and adapted for reception of a manipulatingmeans, the other end portion of said blade body being formed with acurved side edge, said curved side edge being formed substantially on aradius struck about a center positioned to one side of said body andinwardly of the extreme ends of said body, said one side edge beingprovided with saw teeth, said teeth having predetermined sets to thesides of said body to define a generally V-shaped groove when the teethare viewed from the end of said body, an elongated rod of wear resistantmaterial positioned over said side edge and between the tips of saidteeth, and means at the opposite ends of said body for holding said rodsnugly against said teeth.
 2. The structure of claim 1 wherein said lastnamed means includes means for tensioning said rod along the lengththereof and pulling it snugly against the teeth of said body.
 3. Thestructure of claim 1 wherein said last named means includes a detachablecoupling at the shank end of said body and a detachable coupling at theother end of said body, one of said couplings including a threadedfastener for applying tension to said rod.
 4. The structure of claim 1wherein said rod is formed from a tungsten carbide material havingcutting grains embedded therein and exposed through the surface of saidrod for a cutting action.
 5. The structure of claim 1 wherein said rodis positioned against said teeth while leaving air spaces extending fromside to side of said body between said teeth.
 6. The structure of claim1 wherein said rod has a cutting length with a diameter slightly greaterthan the span between adjacent saw teeth.
 7. A saw blade for use incutting hard metals, glass and equivalent hard materials, including anelongated body having a shank end portion adapted to be received by amanipulating means, one side edge of said body being provided with teethwith alternate teeth along said edge being bent outwardly to define adistance between alternate teeth greater than the width of said body, anelongated cutting rod of wear resistant, abrasive particle carryingmaterial positioned over and between the tips of said teeth, and meanscarried by the shank end and other end portion of said body for applyingtension to said rod to draw it snugly against and within the tips ofsaid teeth, said rod having a diameter slightly greater than thethickness of said body.
 8. The structure of claim 7 wherein said oneside edge is curvilinear.
 9. The structure of claim 7 wherein said teethdefine saw teeth for use with other materials when said rod is detachedfrom said body.
 10. The structure of claim 7 wherein said detachablemeans includes a strap carried by said shank end of said body and adetachable strap fitted over the other end of said body, one end of saidrod having abutment means engageable with one strap, and the other endof said rod having adjustable abutment means for engagement with theother strap to thereby apply tension to said rod.
 11. The structure ofclaim 7 wherein said rod is held on saiD blade at the forward end of theblade by a resilient coupling providing tensioning forces to said rod tocompensate for elongation and contraction of said rod due to temperaturechanges.